fs/jffs2/read.c

   1 /*
   2  * JFFS2 -- Journalling Flash File System, Version 2.
   3  *
   4  * Copyright (C) 2001-2003 Red Hat, Inc.
   5  *
   6  * Created by David Woodhouse <dwmw2@infradead.org>
   7  *
   8  * For licensing information, see the file 'LICENCE' in this directory.
   9  *
  10  * $Id: read.c,v 1.38 2004/11/16 20:36:12 dwmw2 Exp $
  11  *
  12  */
  13
  14 #include <linux/kernel.h>
  15 #include <linux/slab.h>
  16 #include <linux/crc32.h>
  17 #include <linux/pagemap.h>
  18 #include <linux/mtd/mtd.h>
  19 #include <linux/compiler.h>
  20 #include "nodelist.h"
  21 #include "compr.h"
  22
  23 int jffs2_read_dnode(struct jffs2_sb_info *c, struct jffs2_inode_info *f,
  24                      struct jffs2_full_dnode *fd, unsigned char *buf,
  25                      int ofs, int len)
  26 {
  27         struct jffs2_raw_inode *ri;
  28         size_t readlen;
  29         uint32_t crc;
  30         unsigned char *decomprbuf = NULL;
  31         unsigned char *readbuf = NULL;
  32         int ret = 0;
  33
  34         ri = jffs2_alloc_raw_inode();
  35         if (!ri)
  36                 return -ENOMEM;
  37
  38         ret = jffs2_flash_read(c, ref_offset(fd->raw), sizeof(*ri), &readlen, (char *)ri);
  39         if (ret) {
  40                 jffs2_free_raw_inode(ri);
  41                 printk(KERN_WARNING "Error reading node from 0x%08x: %d\n", ref_offset(fd->raw), ret);
  42                 return ret;
  43         }
  44         if (readlen != sizeof(*ri)) {
  45                 jffs2_free_raw_inode(ri);
  46                 printk(KERN_WARNING "Short read from 0x%08x: wanted 0x%zx bytes, got 0x%zx\n",
  47                        ref_offset(fd->raw), sizeof(*ri), readlen);
  48                 return -EIO;
  49         }
  50         crc = crc32(0, ri, sizeof(*ri)-8);
  51
  52         D1(printk(KERN_DEBUG "Node read from %08x: node_crc %08x, calculated CRC %08x. dsize %x, csize %x, offset %x, buf %p\n",
  53                   ref_offset(fd->raw), je32_to_cpu(ri->node_crc),
  54                   crc, je32_to_cpu(ri->dsize), je32_to_cpu(ri->csize),
  55                   je32_to_cpu(ri->offset), buf));
  56         if (crc != je32_to_cpu(ri->node_crc)) {
  57                 printk(KERN_WARNING "Node CRC %08x != calculated CRC %08x for node at %08x\n",
  58                        je32_to_cpu(ri->node_crc), crc, ref_offset(fd->raw));
  59                 ret = -EIO;
  60                 goto out_ri;
  61         }
  62         /* There was a bug where we wrote hole nodes out with csize/dsize
  63            swapped. Deal with it */
  64         if (ri->compr == JFFS2_COMPR_ZERO && !je32_to_cpu(ri->dsize) &&
  65             je32_to_cpu(ri->csize)) {
  66                 ri->dsize = ri->csize;
  67                 ri->csize = cpu_to_je32(0);
  68         }
  69
  70         D1(if(ofs + len > je32_to_cpu(ri->dsize)) {
  71                 printk(KERN_WARNING "jffs2_read_dnode() asked for %d bytes at %d from %d-byte node\n",
  72                        len, ofs, je32_to_cpu(ri->dsize));
  73                 ret = -EINVAL;
  74                 goto out_ri;
  75         });
  76
  77
  78         if (ri->compr == JFFS2_COMPR_ZERO) {
  79                 memset(buf, 0, len);
  80                 goto out_ri;
  81         }
  82
  83         /* Cases:
  84            Reading whole node and it's uncompressed - read directly to buffer provided, check CRC.
  85            Reading whole node and it's compressed - read into comprbuf, check CRC and decompress to buffer provided
  86            Reading partial node and it's uncompressed - read into readbuf, check CRC, and copy
  87            Reading partial node and it's compressed - read into readbuf, check checksum, decompress to decomprbuf and copy
  88         */
  89         if (ri->compr == JFFS2_COMPR_NONE && len == je32_to_cpu(ri->dsize)) {
  90                 readbuf = buf;
  91         } else {
  92                 readbuf = kmalloc(je32_to_cpu(ri->csize), GFP_KERNEL);
  93                 if (!readbuf) {
  94                         ret = -ENOMEM;
  95                         goto out_ri;
  96                 }
  97         }
  98         if (ri->compr != JFFS2_COMPR_NONE) {
  99                 if (len < je32_to_cpu(ri->dsize)) {
 100                         decomprbuf = kmalloc(je32_to_cpu(ri->dsize), GFP_KERNEL);
 101                         if (!decomprbuf) {
 102                                 ret = -ENOMEM;
 103                                 goto out_readbuf;
 104                         }
 105                 } else {
 106                         decomprbuf = buf;
 107                 }
 108         } else {
 109                 decomprbuf = readbuf;
 110         }
 111
 112         D2(printk(KERN_DEBUG "Read %d bytes to %p\n", je32_to_cpu(ri->csize),
 113                   readbuf));
 114         ret = jffs2_flash_read(c, (ref_offset(fd->raw)) + sizeof(*ri),
 115                                je32_to_cpu(ri->csize), &readlen, readbuf);
 116
 117         if (!ret && readlen != je32_to_cpu(ri->csize))
 118                 ret = -EIO;
 119         if (ret)
 120                 goto out_decomprbuf;
 121
 122         crc = crc32(0, readbuf, je32_to_cpu(ri->csize));
 123         if (crc != je32_to_cpu(ri->data_crc)) {
 124                 printk(KERN_WARNING "Data CRC %08x != calculated CRC %08x for node at %08x\n",
 125                        je32_to_cpu(ri->data_crc), crc, ref_offset(fd->raw));
 126                 ret = -EIO;
 127                 goto out_decomprbuf;
 128         }
 129         D2(printk(KERN_DEBUG "Data CRC matches calculated CRC %08x\n", crc));
 130         if (ri->compr != JFFS2_COMPR_NONE) {
 131                 D2(printk(KERN_DEBUG "Decompress %d bytes from %p to %d bytes at %p\n",
 132                           je32_to_cpu(ri->csize), readbuf, je32_to_cpu(ri->dsize), decomprbuf));
 133                 ret = jffs2_decompress(c, f, ri->compr | (ri->usercompr << 8), readbuf, decomprbuf, je32_to_cpu(ri->csize), je32_to_cpu(ri->dsize));
 134                 if (ret) {
 135                         printk(KERN_WARNING "Error: jffs2_decompress returned %d\n", ret);
 136                         goto out_decomprbuf;
 137                 }
 138         }
 139
 140         if (len < je32_to_cpu(ri->dsize)) {
 141                 memcpy(buf, decomprbuf+ofs, len);
 142         }
 143  out_decomprbuf:
 144         if(decomprbuf != buf && decomprbuf != readbuf)
 145                 kfree(decomprbuf);
 146  out_readbuf:
 147         if(readbuf != buf)
 148                 kfree(readbuf);
 149  out_ri:
 150         jffs2_free_raw_inode(ri);
 151
 152         return ret;
 153 }
 154
 155 int jffs2_read_inode_range(struct jffs2_sb_info *c, struct jffs2_inode_info *f,
 156                            unsigned char *buf, uint32_t offset, uint32_t len)
 157 {
 158         uint32_t end = offset + len;
 159         struct jffs2_node_frag *frag;
 160         int ret;
 161
 162         D1(printk(KERN_DEBUG "jffs2_read_inode_range: ino #%u, range 0x%08x-0x%08x\n",
 163                   f->inocache->ino, offset, offset+len));
 164
 165         frag = jffs2_lookup_node_frag(&f->fragtree, offset);
 166
 167         /* XXX FIXME: Where a single physical node actually shows up in two
 168            frags, we read it twice. Don't do that. */
 169         /* Now we're pointing at the first frag which overlaps our page */
 170         while(offset < end) {
 171                 D2(printk(KERN_DEBUG "jffs2_read_inode_range: offset %d, end %d\n", offset, end));
 172                 if (unlikely(!frag || frag->ofs > offset)) {
 173                         uint32_t holesize = end - offset;
 174                         if (frag) {
 175                                 D1(printk(KERN_NOTICE "Eep. Hole in ino #%u fraglist. frag->ofs = 0x%08x, offset = 0x%08x\n", f->inocache->ino, frag->ofs, offset));
 176                                 holesize = min(holesize, frag->ofs - offset);
 177                                 D2(jffs2_print_frag_list(f));
 178                         }
 179                         D1(printk(KERN_DEBUG "Filling non-frag hole from %d-%d\n", offset, offset+holesize));
 180                         memset(buf, 0, holesize);
 181                         buf += holesize;
 182                         offset += holesize;
 183                         continue;
 184                 } else if (unlikely(!frag->node)) {
 185                         uint32_t holeend = min(end, frag->ofs + frag->size);
 186                         D1(printk(KERN_DEBUG "Filling frag hole from %d-%d (frag 0x%x 0x%x)\n", offset, holeend, frag->ofs, frag->ofs + frag->size));
 187                         memset(buf, 0, holeend - offset);
 188                         buf += holeend - offset;
 189                         offset = holeend;
 190                         frag = frag_next(frag);
 191                         continue;
 192                 } else {
 193                         uint32_t readlen;
 194                         uint32_t fragofs; /* offset within the frag to start reading */
 195
 196                         fragofs = offset - frag->ofs;
 197                         readlen = min(frag->size - fragofs, end - offset);
 198                         D1(printk(KERN_DEBUG "Reading %d-%d from node at 0x%08x (%d)\n",
 199                                   frag->ofs+fragofs, frag->ofs+fragofs+readlen,
 200                                   ref_offset(frag->node->raw), ref_flags(frag->node->raw)));
 201                         ret = jffs2_read_dnode(c, f, frag->node, buf, fragofs + frag->ofs - frag->node->ofs, readlen);
 202                         D2(printk(KERN_DEBUG "node read done\n"));
 203                         if (ret) {
 204                                 D1(printk(KERN_DEBUG"jffs2_read_inode_range error %d\n",ret));
 205                                 memset(buf, 0, readlen);
 206                                 return ret;
 207                         }
 208                         buf += readlen;
 209                         offset += readlen;
 210                         frag = frag_next(frag);
 211                         D2(printk(KERN_DEBUG "node read was OK. Looping\n"));
 212                 }
 213         }
 214         return 0;
 215 }
 216
 217 /* Core function to read symlink target. */
 218 char *jffs2_getlink(struct jffs2_sb_info *c, struct jffs2_inode_info *f)
 219 {
 220         char *buf;
 221         int ret;
 222
 223         down(&f->sem);
 224
 225         if (!f->metadata) {
 226                 printk(KERN_NOTICE "No metadata for symlink inode #%u\n", f->inocache->ino);
 227                 up(&f->sem);
 228                 return ERR_PTR(-EINVAL);
 229         }
 230         buf = kmalloc(f->metadata->size+1, GFP_USER);
 231         if (!buf) {
 232                 up(&f->sem);
 233                 return ERR_PTR(-ENOMEM);
 234         }
 235         buf[f->metadata->size]=0;
 236
 237         ret = jffs2_read_dnode(c, f, f->metadata, buf, 0, f->metadata->size);
 238
 239         up(&f->sem);
 240
 241         if (ret) {
 242                 kfree(buf);
 243                 return ERR_PTR(ret);
 244         }
 245         return buf;
 246 }